Setting up that Damn SPV =)

Hey Guys,
Just got a VT1 frame and am setting that rear shock up. So far, I'm lost! For some reason I can't understand which chamber needs what amount of pressure. I'm usually good with these things but this one is stumping me. Any hints?

The shock has two schrader valves on it, a red one down on the bottom of the shock, [the 'skinny' end] and a black one up near the top of the 'can' next to a blue adjuster.

The RED schrader valve is your SPV air chamber one. The BLACK one is your main spring air pressure setting.

Basically, you use the shockpump supplied with your bike to pump your body weight plus or minus 20psi into the main air chamber [black schrader valve]. So...if you weigh 170 lbs ready to ride you pump 190 psi into the main chamber.

The SPV [red schrader valve] is set in a similiar manner except this one controls the amount of 'bob' you get when pedalling...and you need to pump half your bodyweight into this valve.

All of these settings are adjustable by varying the amount of air which you pump into each chamber.

You can change the way the bike feels and reacts by changing the amount of pressure in the main or SPV chamber. I have been running 190 main 90 SPV [psi] and find that it is ok for my weight, [180lbs ready-to-ride].

You will have to experiment a bit and find what suits you best for your style of riding and your riding locations.

Be aware that when you unscrew the pump from the valves after pumping air into the chambers, you lose some air into the pump body from the chamber, so allow for this.

Thanks for the reply! One question, I have the 03' frame that comes with the 4way I believe!? So, the SPV chamber is the small one on top and the main chamber is the larger of the two (the big one with the blue rebound adjuster knob next to the valve). Does that sound right? I think I got most of it setup already, according to your info. My main question is how do I know how much to put in the SPV valve? Just Trial and Error? Also, you can adjust the Sag (I think) by using a socket on the SPV chamber?! When I teted this puppy at the LBS they didn't know what the hell to do with it and it was pretty "bobby". I weigh ~205lbs ready to ride if that helps.

The 4 way is a bit different from the 3 way that I have on the '04 VT-2.

I think that in this case you should refer to the Answer site for the settings on your shock. It's similiar to mine but you have the volume adjuster on your 'piggyback' which I don't have on mine. [the red nut]. This controls the volume of air in the piggyback [SPV] which controls the bottoming resistance of the shock during the last 50% of the shock stroke.

Your 'sag' is adjusted by the marks on the piggyback and the O ring on the main body slider.

my suggestion on the 4way

Is to put little stickers near each valve with the air pressure range and set it up at home then ride it and tweek it as you ride to find the right setting. Basically set the piggy back higher then you think and then decrease and I would also start with the sag at 25% and the make the bike more plush from there. Don't forget to adjust the red nut so you don't blow through all your travel!

Re:

I think RainMan's on the money - the more you screw in your volume adjuster the more progressive the shock gets = less chance of blowing through your travel.
Try this sequence (it seems to help with consistency on my 5th Element because the SPV pressure changes when you change the volume): Set your air volume in the main chamber first, then your air volume followed by the SPV chamber pressure. Finally set your sag (because it's affected by the SPV).

oops!!

Also good info here....

Originally Posted by col200

Hey Guys,
Just got a VT1 frame and am setting that rear shock up. So far, I'm lost! For some reason I can't understand which chamber needs what amount of pressure. I'm usually good with these things but this one is stumping me. Any hints?

Giant also supplies information to help on the initial setup of your shock.

Regardless of the color of the cap on the schrader valve of the shock, the big canister is the main air chamber and the small canister is the SPV chamber. Pay special attention to the directions in the Answer product manual about connecting the shock air pump. Screw the head of the shock pump onto the shock until the gauge registers air pressure and then turn it a half turn more. When I first attached my pump, I would turn it until it stopped and was tight. Because of the small area in the linkages that you have to work, it was a bear trying to get off. I think it also made it difficult to remove the pump without losing air from the shock itself.
I have a 2003 VT-1 and while the bike was on order, I did alot of research trying to find what my correct setting would be for my Swinger 4-way.
Do not think too much into this, there is no exact setting. Ask 10 people and you will get 10 different settings. I recommend starting with Giants information at the link shown above, the four step process they show seems to work pretty good. Your body weight minus 20 pounds for the main chamber ( the larger chamber) and 50 - 75% of you body weight in the SPV chamber (small chamber). The adjustment of the SPV volume (the adjustment on the bottom of the SPV chamber that requires a 16mm socket) depends on your riding style. If you like to catch lots of air, I would start at the recommended max setting (3 turns in). If you like to mostly cruise through the woods and singletrack, try a little less. I have found this adjustment to be quite sensitive, only one turn in or out making a big difference in how the shock feels.
I weigh 150 pounds and run 130lbs in the main chamber, 90lbs in the SPV chamber with the SPV volume turned completely out. This sets the sag at 25%. I ride mostly singletrack with an occasional 2 foot drop and this setting works great for me.

Ok, I think I understand. I saw that Giant settings page and that helped quite a bit. My sag is far too much I think. It feels like my steering angle is too steep. It's definatly a change from my NRS steering angle. But man, this SPV is nice. It seems so stiff when I'm doing an all out sprint (not standing of course) and feels like butter at the same time when I fly of an edge. Geez, even riding down a curb is smooth! Seriously! I can see how touchy the Swinger is though. Thanks for all the info guys!